Hepatocellular carcinoma (HCC) is the most found histological type of liver cancer worldwide. The geographical distribution of the incidence of HCC greatly varies in different locations. A high burden of disease is observed in endemic areas where the infection of hepatitis B virus (HBV) is common and in people with chronic liver disease and cirrhosis, especially in China. A majority of liver cancers occur in Asia and China accounts for 47% of all liver cancers globally (1, 2). HBV-related HCC always lead to a poor prognosis, meanwhile portal hypertension (PH) related hypersplenism is a common manifestation of HCC, leading to leucopenia, thrombocytopenia, and anemia. Advanced cases of HCC with end-stage liver diseases are recommended for liver transplantation (3). Nevertheless, due to the high cost and shortage of donors, liver transplantation is controversial for patients with hypersplenism and an adequate hepatic reserve. Hypersplenism can also lead to hepatic damage, increase the magnitude of hepatic fibrosis, and cause severe functional abnormalities, including thrombocytopenia. Thrombocytopenia heightens the risk of long-term bleeding, limiting the possibility of most treatments and worsening the prognosis (4).

The European Association for the Study of the Liver (EASL) and the American Association for the Study of Liver Disease (AASLD) recommend performing hepatectomy only for patients with HCC without hypersplenism (5, 6). However, patients with good liver function reserve undergo simultaneous hepatectomy and splenectomy, especially in East Asian countries like China and Japan (7, 8). Despite this surgical intervention, the treatment for hypersplenism in HCC patients is still a controversial issue. The spleen is an important functional unit of the immune system, and as the hepatic disease progresses the immune function of the spleen is gradually compensated and resulted in hypersplenism, which further develops dysfunctional and enlarged spleen (9). In such a situation, spleen is always believed to negatively affect the immune function of the liver and the prognosis of HCC (10). However, research evidence on whether hypersplenism affects the prognosis of patients with HCC following hepatectomy is still insufficient due to the heterogeneity of study population and lacking short-term results in some previous studies. Therefore, we carried out this retrospective study of a single center aimed to elucidate the effects of hypersplenism on the prognosis of patients with HBV-related HCC following hepatectomy.

HBV infection is an important risk factor for HCC, especially when occurred simultaneously with chronic liver disease and even cirrhosis (14), and these patients often suffered from hypersplenism (15). The treatment of hypersplenism in patients with HCC is controversial. Since severe liver dysfunction and low platelet counts are associated in these cases, managing perioperative bleeding and postoperative liver failure is of the main concern. Sometimes, these cases cannot be surgically managed (16). In addition, the outcome from simultaneous hepatectomy and splenectomy was inconsistent in different studies (12, 17). No unified opinion on the treatment of HBV-related HCC with hypersplenism exists currently. Therefore, this study further aimed to reveal the clinical outcome differences in these patients. We found that hypersplenism significantly worsened the prognosis and need to be treated more actively.

The spleen is an important part of the immune system, but its normal function is affected in the presence of liver cirrhosis and compensatory hypersplenism (18). Jasnis et al. found that the immune function of the spleen was decreased with the progression of liver cancer (19). The spleen can also affect the liver microenvironment through complex liver-spleen cross-talks. Spleen-derived immune cells can directly change the composition of hepatic leukocytes by releasing cytokines or being recruited by the liver, forming an immune microenvironment that is conducive to tumor growth and development (20). On the other hand, tumor-derived factors alter the hepatic microenvironment, gradually increasing the immunosuppressive nature and tumor-stimulating functions of the spleen (20). Some previous studies revealed that the marginal area of the splenic tissue from patients with tumors contained a large number of CD11b + Gr-1intLy6Chi cells, resulting in the abnormality of the T cell receptor CD3 complex, inhibiting T cell immune function, and leading to tumor immune tolerance (21). Our results supported the above findings by exhibiting the severity level of hypersplenism directly associated with prognosis results. Splenectomy in mice eliminated the tumor-induced tolerance by reducing the proportion of myeloid-derived suppressor cells in peripheral blood, restoring lymphocyte function, and increasing the natural killer cells (22). The spleen also affected the progress of liver regeneration through transforming growth factor β1 (TGF-β1), hepatocyte growth factor (HGF), thrombospondin-1 (TSP-1), and cytokines such as TNF-α and IL-6 (23). Our previous research found that splenectomy attenuated liver fibrosis by reducing the expression of LIGHT [Tumor necrosis factor superfamily 14 (TNFSF14; also known as LIGHT)] (24). It was speculated that hypersplenism showed adverse effects on the prognosis of patients with HCC complicated with cirrhosis. To further explore the effect of hypersplenism on prognosis and reduce bias, we retrieved basic and clinical data from patients who were followed for approximately ten years for retrospective analysis and evaluated potential confounding variables that might have affected the prognosis.

The baseline data was inconsistent with HBV-DNA copies and ALB levels as determined from our study. The patient with hypersplenism might possibly have decompensated the liver cirrhosis very early and received antiviral therapy earlier. Liver cancer occurring under this condition usually indicating a poor hepatic function. Patients with HCC without hypersplenism often compensated for liver cirrhosis, but many of them were asymptomatic. Most of these patients did not receive standard antiviral therapy, abut their hepatic function preserve was still acceptable. Thus, patients with hypersplenism had lower albumin levels and their HBV-DNA copies was mostly negative. In most patients who received standard antiviral treatment before surgery, the number of HBV-DNA copies was reduced to a normal level on the 6th-month follow-up. Hypersplenism prolonged hospital stay and increased the frequency of postoperative blood transfusions. Regarding the postoperative complications, complication categories were found statistically differed among the three groups. Since the hypersplenism was not resolved in these cases, the low WBC count, reduced PLT count, and coagulation abnormalities were not improved. The decline in platelet counts can increase the risk of internal and external bleeding (25). Unameliarated hypersplenism might increase the incidence of ascites and deteriorated hepatic function in patients with HCC (26). Therefore, patients with hypersplenism should receive more meticulous perioperative care to promote their recovery. Regarding the long-term outcome, the mean survival time and mean recurrence time were greatly reduced in HCC patients accompanied with hypersplenism, and further decreased with the severity of hypersplenism. On Kaplan-Meier analysis, the OS and DFS in patients with HCC were decreased significantly with the increasing severity of hypersplenism, and they were significantly different among the groups. This result may have been due to the postoperative inflammatory response caused by hypersplenism, and systemic inflammation that was associated with poor prognosis in HCC. Tumor cells proliferate and metastasize by promoting angiogenesis, damaging DNA structure and function, inhibiting apoptosis, and evading immunosurveillance via inflammation. Therefore, aggressive treatment of postoperative inflammation may be critical for improving the prognosis of HCC patients. Furthermore, liver function damage and even liver failure may occur in patients with HCC and hypersplenism after surgery (27), leading to poor OS.

Multivariate analysis revealed that hypersplenism and tumor size of >5 cm were found to be independent prognostic factors for both OS and DFS among patients with HBV-related HCC. Nevertheless, positive HBV-DNA copies and serum AFP levels of >400 ƞg/ml were independent prognostic factors only for OS. Factors other than hypersplenism were similar in the groups at baseline. Specific to tumor size, the patients with tumor size greater than 5 cm had a significantly worse prognosis (28) because vascular infiltration and tumor differentiation were closely related to the size of HCC (29). In addition to the effects of hypersplenism on tumor immune tolerance, hemodynamic abnormalities resulting from hypersplenism can induce abnormal liver function, influencing the outcome (4). Platelet counts were decreased significantly in hypersplenism, and thrombocytopenia aggravated the progression of liver abnormalities (30). Platelets stimulated the proliferation of liver sinusoidal endothelial cells (LSEC) and accelerated the DNA synthesis in hepatocytes (31). Furthermore, platelets can directly interact with hepatocytes to induce hepatic regeneration. Coculture experiments found that platelets that are in contact with hepatocytes triggered the secretion of growth factors, including IGF-1, HGF, and VEGF, and thus induced the proliferation of hepatocytes (32). But in contrast to mice, human platelets fail to secrete enough HGF. Therefore, this mechanism may not apply to humans. As for the role of the spleen in patient prognosis, a retrospective study with long-term follow-up by Zhang et al. showed consistent results with our study (12). But the definition of the pathological spleen as splenomegaly and hypersplenism in this article was different from that in our study. Our study removed this bias and targeted the investigation of hypersplenism. As the severity of hypersplenism increased, laboratory parameters were further affected. The negative regulation of the liver was enhanced, the beneficial effects diminished, and the imbalance between them became more severe. This outcome was consistent with our results, and both mild and severe hypersplenism were found to be independent risk factors for OS and DFS.

Subgroup analysis showed good internal consistency for the effect of hypersplenism on survival. Although statistically significant, the p-values associated with HR at different subgroup levels should be interpreted with caution (33). For example, they were female patients and with Child-Pugh B in the OS analysis, and patients with advanced tumor stage (BCLC C; TNM III; CNCL III) and patients with Child-Pugh B in DFS analysis. The associated P-values for HR in the above groups were not significant. This insignificance could be explained by the intergroup variability, which may have increased the proportion of patients with extreme values or with short follow-up time. This may have resulted in the inability to draw an accurate conclusion. Patients with advanced tumor stage and poor liver function had poor prognoses regardless of the cooccurrence of HCC and hypersplenism (34). Thus, the effect of hypersplenism on prognosis in these patients might have been masked, making the conclusion insignificant. Hence, the intervention on the spleen should be carried out as early as possible. It is uncertain whether hypersplenism can reduce the recurrence rate. But some previous studies showed that splenectomy before hepatectomy or simultaneous hepatectomy and splenectomy could both increase the DFS rate of patients with HCC and hypersplenism, while splenectomy before hepatectomy might reduce the hypersplenism without increasing the risk of surgery (35). However, these findings still need further verifications.

This study still has some limitations. First, selection bias may not have been avoided in this type of nonrandomized study. Second, all samples came from a single medical center. Third, few cases didn’t receive complete follow-up due to the study time limitation. Therefore, expansion of the sample size or randomized controlled trial should be carried out to investigate the influence of hypersplenism on patients with HCC and hepatitis B cirrhosis following hepatectomy.

In conclusion, hypersplenism affected perioperative and postoperative results and prognosis in patients with HBV-related HCC. The hypersplenism prolonged the hospital stays, increased the rate of postoperative blood transfusions, and increased the incidence of complications. With the increasing severity of hypersplenism, the prognosis of patients gradually deteriorated. Additionally, severity of hypersplenism could be used as an important prognostic factor for tumor recurrence and long-term survival of patients.